Chapter 9

Report
Managing Information Technology
6th Edition
CHAPTER 9
BASIC INFORMATION
SYSTEMS CONCEPTS
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1
The Systems View
What is a system?
System
Information
System
• A set of interrelated components that must
work together to achieve some common
purpose
• The collection of IT, procedures, and people
responsible for the capture, movement,
management, and distribution of data and
information
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THE SYSTEMS VIEW
Seven key system elements
1. Boundary
2. Environment
3. Inputs
4. Outputs
5. Components
6. Interfaces
7. Storage
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THE SYSTEMS VIEW
Seven key system elements
1. Boundary
• Delineation of which elements are
within the system and which are
outside
2. Environment
• Everything outside the system
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THE SYSTEMS VIEW
Seven key system elements
2. Inputs
• Resources from the environment that are
consumed and manipulated within the
system
3.
4. Outputs
• Resources or products provided to the
environment by the activities within the
system
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THE SYSTEMS VIEW
Seven key system elements
5. Components
• Activities or processes within
the system that transform
inputs into intermediate forms
or that generate system outputs
• Components can be viewed as
subsystems
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THE SYSTEMS VIEW
Seven key system elements
6. Interfaces
• The place where two components or the
system and its environment meet or interact
7. Storage
• Holding areas used for the temporary and
permanent storage of information, energy,
materials, and so on
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THE SYSTEMS VIEW
Examples of System Components from Payroll
Inputs
• Time cards, vouchers
Outputs
• Paychecks, W-2 Forms
Components
Interfaces
Storage
• Calculate total pay, subtract deductions
• Match time cards to employees, sort paychecks by
department
• Employee benefits, Pay rates
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THE SYSTEMS VIEW
Component Decomposition
• Some system components can be viewed as systems
with their own sets of interrelated components and are
called subsystems
• Hierarchical decomposition is the process of breaking
a system down into successive levels of subsystems
• Five important goals of hierarchical decomposition:
1.
2.
3.
4.
5.
Cope with system complexity
Analyze or change only part of the system
Design and build each subsystem at different times
Direct the attention of a target audience
Allow components to operate more independently
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THE SYSTEMS VIEW
Organizations as systems
• One useful framework for examining how
information systems fit into organizational
systems is based on the Leavitt diamond
• Four fundamental components in an organization
are linked
–
–
–
–
People
Organizational structure
Information Technology
Business Processes
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10
THE SYSTEMS VIEW
Organizations as systems
• Leavitt Diamond
– If one is component is changed, the others will
likely be affected as well
– For example, new software may have the
following effects:
• People have to be retrained
• Business processes need to be redesigned
• Organizational structures must be modified
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11
THE SYSTEMS VIEW
Systems analysis and design
• IT leaders understand that changes in information
systems affect the entire organizational system
• One process used in developing new systems that
takes into account the systems view is Systems
Analysis and Design (SA&D)
• Two key principles:
– Choose an appropriate scope
– Logical before physical
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THE SYSTEMS VIEW
Systems Analysis and Design
• SA&D has five key design principles
• Two key principles stem from key systems
characteristics:
1. Choose an appropriate scope
• Selecting the boundary for the IS greatly influences
complexity and success of the project
2. Logical before physical
• You must know what an IS is to do before you can
specify how a system is to operate
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THE SYSTEMS VIEW
Systems Analysis and Design
• SA&D has five key design principles
• The other three principles are problem-solving steps:
3. A problem is actually a set of problems and an
appropriate strategy is to keep breaking down a problem
into smaller, more manageable problems
4. A single solution is not usually obvious to all
stakeholders, so alternative solutions representing all
parties should be generated before a final solution is
selected
5. The problem and your understanding of it could change;
thus a staged approach that incorporates reassessments
and incremental commitment to a solution is best
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Business Processes
• In the 1990s many organizations changed
from a more functional approach to a more
process-oriented approach to better compete
globally
• Experts urged companies to radically change
the way they did business by starting with a
“clean slate” and utilizing IT
“Don’t automate;
obliterate!”
- Michael Hammer
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Business Processes
• These changes became known as business
process reengineering
Business process reengineering (BPR)
• Radical business redesign initiatives that attempt to
achieve dramatic improvements in business
processes by questioning the assumptions, or
business rules, that underlie the organization’s
structures and procedures
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Business Processes
How IT Enables New Ways to Work
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Business Processes
Six Key Principles for Redesigning Business Processes
• Organize business processes around outcomes, not tasks
• Assign those who use the output to perform the process
• Integrate information processing into the work that
produces the information
• Create a virtual enterprise by treating geographically
distributed resources as though they were centralized
• Lick parallel activities instead of integrating their results
• Have people who do the work make all the decisions,
and let controls built into the system monitor the
process
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Processes and Techniques
Systems development life cycle (SDLC)
• Three phases of information system development:
1. Definition: end users and systems analysts conduct a
multistep analysis of the current business operations and the
information system or systems in the area of concern
2. Construction: designing, building, and testing of a system that
satisfies the requirements developed in the Definition phase
3. Implementation: install the new system, which often involves
converting data and procedures from an old system
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Structured Techniques
Structured Techniques
• Tools to document system needs, requirements,
functional features, dependencies, and design
decisions
• Procedural-oriented
– Most common
– Include data-oriented, sequential, process-oriented activities
• Object-oriented
– Newer approach
– Often used for GUIs and multimedia applications
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Structured Techniques
• Procedural oriented techniques describe
what you have, define what you want, and
describe how you will make it so
• Different techniques are used to create the
following three models:
1. As-Is
2. Logical To-Be
3. Physical To-Be
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Structured Techniques
1. As-Is Model
•
Must identify existing processes, external participants,
other databases or applications, and inputs and outputs
2. Logical To-Be
•
•
•
•
High-level model of a nonexistent new system
Identifies processes and data
Does not identify who does activity, where accomplished,
or type of hardware or software
Describes “what” rather than “how”
3. Physical To-Be
•
Requires technology expertise to map the logical
requirements to available technology
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Structured Techniques
Techniques for the As-Is Model
• Context Diagram
– Positions the system as a whole with regard to
other entities and activities with which it
interacts
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Structured Techniques
Techniques for the Logical To-Be Model
• Data Flow Diagram (DFD)
– Shows the flows of information through the
system
– These consist of four symbols representing:
•
•
•
•
External Entity
Data Flow
Process
Data Store
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PROCESSES AND TECHNIQUES
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Structured Techniques
Techniques for the Logical To-Be Model
• Data Dictionary/Directory
– Used to define data elements
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Structured Techniques
Techniques for the Logical To-Be Model
• Entity-Relationship Diagram (E-R Diagram or
ERD)
– Used to define relationships among entities
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Structured Techniques
Techniques for the Physical To-Be Model
• Draft Layouts
– Represents user interface design
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Structured Techniques
Object-Oriented (O-O) Techniques
– Primary advantage is object reuse
– Can enable quick prototyping
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Structured Techniques
Core Object-Oriented Concepts
– Encapsulation
–
–
An object contains data and related operations
Allows loosely coupled modules and reuse
– Inheritance
–
One class of objects can inherit characteristics from others
– Polymorphism
–
The ability to treat child objects the same as parent objects
(i.e. call methods exactly the same)
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Structured Techniques
Unified Modeling Language (UML)
– A set of standardized techniques and notations
for O-O analysis and design
• There are several types of UML diagrams
used to design systems including
– Use-case diagram
– Class diagram
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UML
Unified Modeling Language (UML)
• Use Case Diagram
– Represents the interaction of users with the
system
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UML
Unified Modeling Language (UML)
• Class Diagram
– Represents each object’s attributes, methods, and
relationships with other objects
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Information Systems Controls
• All businesses face security risks and only a
small percentage of those risks involve IT
• IT can be used to mitigate some business risk
through the addition of controls
• There are three types of control mechanisms
1. Management policies
2. Operating procedures
3. Auditing function
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Information Systems Controls
• Controls can be built into the information
system itself throughout the SDLC
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